Means for handling a ship&#39;s lifeboat



June 16, 1936.

MEANS FOR HANDLING A SHIPS LIFEBOAT A. P. SCHAT Filed Oct. 25, 1953 [NVSNTOR a; WWW

Patented June 16, 1936 UNETED STATES PATENT OFFIQE MEANS FOR HANDLING A SHIPS LIFEBOAT 2 Claims.

This invention relates to a ships lifeboat.

The main object of the invention is to provide for a manually operable davit installation, which enables the boat to be launched also on the high side of a vessel having a considerable list, requires relatively very little power for its operation, permits of deck space being gained for passengers and increases the access of light to deck cabins, if any.

With these and other objects in view, I suggest to suspend the lifeboat from a lufling davit, or a pair of such davits adapted to travel along a trackway disposed athwart-ships and to associate said davit, or davits, with rigid means, such as an expansible and contractible member for positively forcing the davit, or the davits, along said trackway towards or away from the water, and for lufiing the same, if so desired.

The invention is illustrated in the accompanying drawing, in which Fig. 1 is a general view of an installation embodying the invention,

Fig. 2 is a side view of the davit and of its trackway, looking from the left hand side in Fig. 1, and

Fig. 3 shows the expansible and contractible member, drawn to an enlarged scale, partly in elevation and partly in longitudinal section.

As shown, the lifeboat 4 is suspended from a pair of lufi'ing davits, of which only one has been illustrated and designated by the numeral 5.

means for handling Said davit has an enlarged base or foot portion forming a slide fitted with two pairs of rollers 6, 6 and l, l, by means of which the davit is adapted to travel on the steel deck 8 towards and away from the water. Said rollers are rotatable about trunnions 9, 9' and l0, II), which laterally project therefrom and are guided by the lower faces of the inturned horizontal top flanges of two Z-irons ll, l2, the bottom flanges of which are fastened to the steel deck 8, it being understood that the said top flanges are flush with the wooden deck l3 A certain distance above the trackway ll, l2, the davit 5 is provided, on its outboard side, with laterally extending trunnions l4, I5 adapted, at the end of the outward movement of the davit along its track, to enter into notches l6 of a bracket l1 bolted or otherwise secured to the steel deck near the edge thereof. Said bracket is provided with some conventional means whereby the trunnions l4, I5, after entering the said notches l6, may be locked so as to be prevented from inboard movement but to have freedom of rotary movement within the notches of the brackets which, therefore, act both as bearing blocks and as stoppers.

As clearly seen from Fig. 1, the Z-irons ll, I2 end a certain distance fromthe stoppers l7, 5 whereby gaps 58 are formed allowing the trunnions 9, 9' to pass. The Z-irons ll, l2 are each provided with a recess l9 spaced from gap l8 through a distance equal to that between the pairs of rollers 6, 6' and 'l, 1. 10

Intermediate the gaps l8 and the recesses l9, the runners M, 2 have additional recesses 20, and intermediate the pairs of rollers 9, 9 and l0, ill the davit foot is provided with laterally projecting pins 2| which, during the travelling 15 movement of the davit along its trackway, also engage the lower faces of the top flanges of the runners H, I2.

Between its top and its 'foot, the davit 5 is hinged to a substantially horizontal, expansible and contractible member 22 shown in further detail in Fig. 3, and whose inner end is pivoted as at 23 to a deckhouse or other fixed structure of the vessel 1 at a height of say 6' 10" above the deck. Said member is composed of a tube 24 provided with a lug 25 for receiving the horizontal pivot 23, and with a nut member 26 at its outboard end operatively engaged by a hollow screw spindlle 21. The latter, the inward end of which is provided with a collar 21a, also has a nut member 28 at its outboard end in engagement with a solid screw spindle 29, the inner end of which is provided with a collar 29a and the outer end of which carries a mitre wheel 38 (Fig. 2) meshing with a second mitre wheel M on a horizontal shaft 32. Said shaft runs in the longitudinal direction of the vessel and is supported in bearings of the davit 5. Its free end carries a cast wheel 33 having a circumferential groove 34 of V-shaped cross section, it being understood that the side walls of said groove are not machined, but rough. Passed around wheel 33 is an endless operating rope 35.

It may be stated here that the pitch of the screw thread on spindles 21 and 29 is so small that both spindles are self-braking, so that there is no danger for the davit on the low side of a vessel having a considerable list to move downhill towards the water under the influence of gravity only. 50

Near its foot, the davit 5 is provided with a small bollard 36, and coaxially with shaft 32 it has a fixed guide roller or sheave 37 serving as a fairlead for the boats fall '38.

The lower end of the davit is further provided 55 with a rest 39 for supporting the keel 49 of the stowed boat. Said rest is engaged by one end of the boat lash M, the ether end of which is adapted to be secured to the davit by means of a slipguard link not shown on the drawing.

The boat 4 is suspended from the davit 5 in the ordinary manner by means of manila falls 38, each of which is passed over sheaves 42 rotatably mounted in the head of the corresponding davit 5 and sheaves 43 rotatably mounted in the steel house 44 of the lower block. Said house is fitted with an eye 45 which through a slipguard link 48 and a chain 47 is suspended from the davit head.

The modus operandi of the described installation is as follows. 7

If the davit 5 and the boat 4 assume the position shown in full lines, the multiple telescopic screw spindle gear is collapsed and has its minimum length. If, then, wheel 33 is turned by means of rope 35, the solid screw spindle 29 will be rotated through the medium of the mitre wheels 3| and 30, whereby, owing to the cooperation of said screw spindle with its nut 28, the member 22 is expanded. It is to be remarked that, since the V-groove in the wheel 33 is not machined, so that its walls have a rough surface, the rope 35 cannot slip under any pull that is likely to be exerted on the hauling part thereof.

If screw spindle 29 is rotated, its nut 28 will remain stationary, abstracting from its axial movement, until it is engaged by collar 29a. Thereupon, further rotation of screw spindle 29 will cause rotation of the hollow screw spindle 27 relative to its nut 26, whereby said last spindle is screwed out of its tube 214 and the member 22 is still further expanded, until collar 21a abuts against nut 26, when member 22 has reached its maximum length.

During the first part of the expansion of member 22, the davit 5 is moved in. outward direction along its trackway ll, I2, until its trunnions l4, l5 abut against the bottom walls of the notches [6 of the stopper IT, in which notches said trunnions are locked against inboard movement, either manually or automatically. The position then assumed by the davit is shown by dotted lines. As will be seen, the boat 4 is then halfway outboard with its keel 48 vertically above the side of the vessel, and may be left there as long as the vessel is at sea. With the boat in this position, the light has better access to deck cab ins, if any, and a considerable amount of deck space is gained for the passengers. Preferably, the inboard parts of the tracks for the davit are then covered with wooden grates so as to provide for a flush walking space.

When it is desired to launch the boat, the lashings 4| are released. This can be done in the usual manner by means of slip-guard links (not shown) on the inboard side. Thereupon, the member 22 is further expanded by again pulling on the rope 35, whereby the davit 5 is swung in anticlockwise direction about its trunnions H5, I5, until the boat has reached its extreme outboard position and can be lowered.

It will be seen from the drawing that in the outboard position of the davit 5 the trunnions 9, 9 and l0, ID of the rollers 6, 6' and i, l

- register with the gaps l8 and 19, respectively, and

that the laterally projecting pins 2i then register with the gap 20, so that the davit has freedom of swinging motion about its trunnions I4, !5.

If the vessel has a considerable list, the davits on the low side need not be swung out, as the boats on that side already assume a position vertically above the water, after their lashings 4| have been released. Since the screw spindles 27 and 29 are self-braking, the davit in its dotted line position cannot swing out unless wheel 33 is positively turned by means of the rope 35.

It will further be understood that, when the boat is pro-vided with so-called skates, as described, for instance in my prior British Patents 252,014, January 6, 1927; 255,727, July 26, 1926; 257,300, August 26, 1926; and 259,148, October 7, 1926, the boat can be launched without the davit in its dotted line position being swung out (provided the davit is not on the high side of a heavily listed vessel) and the skates will then guide the boat down the ships hull. When the boat is so lowered, it will be pressed against the ships side owing to the top blocks of its tackles being inboard, whereby the embarcation of passengers and crew is facilitated.

In order that the boat can be lowered, it is necessary first to release the slipguard link 46, and thereupon to pay out the fall 38. In this connection it is remarked that the provision of the chain 47 with its slipguard link 46 provide a ready means for relieving the fall, and thereby the sheaves and pins of the blocks, from tension whenthe boat assumes its stowed position. In order that the boat may thus be suspended from the chains 47, it is necessary to first hoist it by its falls until the slipguard links 46 can be closed and locked.

The fall 33, which is passed over the sheaves of thelower block and of the top block, is first led over pulley 37, which is secured to the davit arm and locked against rotation, and thereupon belayed on bollard 36 secured to the davit arm on the inboard side thereof. This construction has the advantage that noholes are to be drilled in the steel deck 8 for fastening said bollard and also, that the bollard follows the lateral and swinging movements of the davit, so that the men who pay out the fall can always keep their eyes upon the boat, even when the latter is near the surface of the water. Owing to the presence of the fair lead 31, which, during the lowering of the boat, by its friction takes up a considerable part of the tension in the fall, the bollard 36 may be relatively small. When the boat is to be hoisted, however, the fall is taken offsaid :fixed fairlead and its hauling part then runs from the top block directly to a removable footblock on deck and thence to a winch, both not shown.

- Obviously, the unique arrangement wherein the luffing davit, in addition to its swinging movement, must also be adapted to travel through a considerable distance over the deck, requires an expansible member 22 of considerable maximum length. Up till now, members of this type always consist of a tube provided with a nut, and one single screw spindle engaging said nut, so that their maximum length is at most equal to twice its minimum length. With a construction as shown in Fig. 3, however, wherein the screw spindle 21 is hollow and is itself provided with a nut- 28 coacting with a second screw 29, the length of member 22 in fully expanded condition is about thrice that in collapsed condition, so that said construction is especially adapted for use with davits of my novel type. It will be remarked that member 22, which is substantially horizontal when the davit assumes its inboard position shown in full lines, remain substantially horizontal until the davit has reached its outboard position illustrated in dotted lines. Only thereafter, further rotation of wheel 33 will cause the davit to swing about its trunnions I 4, l5, during which movement the point in which member 22 engages the davit first rises and thereafter descends. However, since during this swinging movement member 22 has already a considerable length, its deviation from the horizontal will not become very appreciable, so that said member always engages the davit under a favorable angle.

With a view to the fact that the lateral outboard movement of the davit will, as a rule, require less power than the first part of the swinging movement, the pitch of the screw spindle 29 preferably exceeds that of screw spindle 21, although it must remain below the limit at which it would lose its self-braking action.

What I claim is:-

1. In combination, a davit adapted for lufling 'movement and a telescopic member for controlling said movement, said member comprising a tubular element provided with female thread, a hollow externally threaded screw spindle engaging said female thread so as to be freely rotatable and axially movable relative to said tubular element and provided with female thread, having a pitch different from that of its external thread, a second screw spindle engaging the female thread of the hollow screw spindle so as to be freely rotatable and axially movable relative to both said hollow screw spindle and said tubular element, and means on said hollow screw spindle and on said second screw spindle for limiting said axial movements.

2. In an installation for launching a lifeboat on board a vessel comprising a substantially straight trackway provided athwartships on a vessel, an upright davit arm movable on said trackway and maintained in upright position during travel thereon, substantially horizontal pivot means for limiting the outboard movement of said davit arm, said pivot means including a pivot element on the davit arm and a pivot element fixed on the ship above the trackway and engageable by the first mentioned pivot element when the davit arm is in outboard position, whereby said davit arm may perform a lufiing motion about the horizontal axis of said pivot means, and means for moving the davit arm along said trackway and for swinging it about said axis.

ANE PIETER SCHAT. 

